题目请戳这里 题目大意:给一张无向图,现在要去掉一些边,使图仍然连通,求不能去掉的边. 题目分析:就是求无向图的桥. tarjan算法跑一遍,和无向图割点十分类似,这里要找low[v] > dfn[u]的边(u,v)便是割边,因为v是u的孩子,但是v无法访问到u的祖先,那么断开这条边原图必不连通,因此这是桥.这题会有平行边,平行边必定不是桥.所以dfs的时候要判断一下. 详情请见代码: #include <iostream> #include<cstdio> #include…

题目大意:求无向图的割边编号. 割边定义:在一个连通图中,如果删去一个边e,图便变成不连通的两个部分,则e为该图的割边. 求法:边(u,v) 不是割边,当且仅当边(u,v)在一个环内.因此所有不在环内的边就是割边,我们要找到它.对图进行Dfs,对每个节点盖上时间戳DfsN,Dfs的方式形成了一棵搜索树.不在环内的边一定在搜索树中(证明:假设不在环内边e不在搜索树中,则Dfs时要访问该边的to点就会经过另外一条边e'.Dfs的出发点是相同的,因此必然e,e'在一个环内),我们要找到它.如果边(u,…

题目要输出一个无向图的所有割边.用Tarjan算法: 一遍DFS,构造出一颗深度优先生成树,在原无向图中边分成了两种:树边(生成树上的边)和反祖边(非生成树上的边). 顺便求出每个结点的DFS序dfn[u] 和 每个结点能沿着它和它的儿子的返祖边达到的结点最小的DFS序low[u]. 一条边(u,v)是割边当且仅当—— low[v]>dfn[u] 注意具体实现时,无向图的边在邻接表中有正反两条边,那么如果一条边是树边了,另一条边不应该是反祖边,要忽略. #include<cstdio>…

一眼题:找所有的桥,然后求最小权值 但是有很多坑点 1:如果本来不联通 输出0,(这个坑我知道) 2:但是还有一个坑,就是当整个连通,最小桥的权值是0时,也必须派一个人去,wa了无数遍(还是太年轻) #include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <cmath> #include <string> #include…

#include <iostream> #include <cstring> #include <string> #include <cstdio> #include <cmath> #include <algorithm> #include <vector> #include <queue> #include <map> #define inf 0x3f3f3f3f #define eps 1e-…

Burning Bridges Time Limit: 5 Seconds      Memory Limit: 32768 KB Ferry Kingdom is a nice little country located on N islands that are connected by M bridges. All bridges are very beautiful and are loved by everyone in the kingdom. Of course, the sys…

题目地址:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2588 Burning Bridges Time Limit: 5 Seconds      Memory Limit: 32768 KB Ferry Kingdom is a nice little country located on N islands that are connected by M bridges. All bridges are very…

Caocao's Bridges Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 4254    Accepted Submission(s): 1337 Problem Description Caocao was defeated by Zhuge Liang and Zhou Yu in the battle of Chibi. B…

Burning Bridges Time Limit: 5 Seconds Memory Limit: 32768 KB Ferry Kingdom is a nice little country located on N islands that are connected by M bridges. All bridges are very beautiful and are loved by everyone in the kingdom. Of course, the system o…

Burning Bridges Time Limit: 5000ms Memory Limit: 32768KB This problem will be judged on ZJU. Original ID: 258864-bit integer IO format: %lld      Java class name: Main   Ferry Kingdom is a nice little country located on N islands that are connected b…